Groeneweg JW, Roze JF, Peters EDJ, et al. - In this national multicenter study, researchers analyzed serial plasma samples of adult granulosa cell tumors (aGCTs) patients for determining the presence of circulating tumor DNA (ctDNA) harboring a FOXL2 (transcription factor) or TERT promoter mutation, as well as to ascertain whether it has clinical value for monitoring disease. This analysis involved 21 patients with primary (n = 3) or recurrent (n = 18) aGCT harboring a FOXL2 402C > G and/or TERT (C228T or C250T) promoter mutation. Per findings, a correlation with disease progression and treatment response was shown by both FOXL2 mutant ctDNA and TERT promoter mutant ctDNA levels in most of the patients. The majority of aGCT patients had FOXL2 mutant ctDNA and a smaller subset of patients exhibited the presence of TERT promoter mutant ctDNA. As inferred based on findings, both FOXL2 and TERT mutant ctDNA detection may be clinically valuable for disease monitoring.